This is propably 3010 .. wich means "please reboot". To fix it simply add a second exit code line to your package (and set reboot flag) .. see above.
For German version use {AC76BA86-7AD7-1031-7B44-A70500000002} in In uninstall. Seems 3rd just change the third part is of the alfanumeric chain (1033) into NLS ident.code, which is:German: 1031Polish: 1045